Indigo-blue sulfur dye and process of making same.



Patented August 18, 1903.

A l OSKAR KALTWASSER AND MAX GAUMER, OF BERLIN, GERMANY, AS-

' 'SIGNORSH on BERLfN, GERMANY.

O ACTIEN GESELLSCHAFT FUR ANILIN FABRIKATION,

INDIGO-BLUE SULFUR DYE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent N 0. 736,403, dated August18, 1903. Application filed May 21. 1903. Serial No. 158,104. (Nospecimens.)

T aZZ whom, it may concern.-

Be it known that we, OSKAR KALTWASSER and MAX GAUMER, of Berlin, in theKingdom of Prussia, German Empire, have invented new and usefulImprovements in the Prod uction of Indigo-Blue Sulfur Dye; and we dohereby declare that 'the following is a full,

. a 'clear, and exact description of the invention, which will enableothers skilled in the art to which it appertains to make and use thesame.

It is known that by heating compounds of the indophenol series withsulfur and alkali sulfid coloringmatters of various shades dyeingunmordanted cotton direct may be obtained. (Compare German Patent No.132,212.) The process indicated in the aforementioned patent consists inheating an indophenol with sulfur and alkali sulfid at first for severalhours to about 140 and then raising the temperature for a short time to160. According. to the directions given in the examples of this patentthe sulfur and alkali sulfid are employed in the proportions of one partofsulfur'to four parts of crystallized sodium sulfid.

Now we have observed that when subjecting the typical indophenol i tothe action of sulfur and alkali sulfid in the aforementioned way,prescribed by the German Patent No. 132,212, a product is obtained whichhas but a very slight affinity for the fiber and dyes unmordanted cottonweak bluish shades which are neither fast tosoaping nor washing.According to our observations this unsatisfactory result is due to thefollowing facts-namely, the high temperature employed, and, moreover,the relative proportions of sulfur and sulfid prescribed in the GermanPatent No. 132,212 by the inventor. Especially the latter point is ofgreat importance and is in'our opinion the reason why sulfureteddyestuifs of technical interest have up to the present not been obtainedfrom the aforementioned indophenol or its nearest homologues. We havediscovered that for the preparation of a valuable dyestuff. from theseindophenols it is absolutely necessary to perform the process with suchquantities of sulfur and sulfid of sodium that upon one molecule ofsodium sulfid at least four atoms of sulfur are employed. If thequantity of sulfur is reduced toa proportion corresponding to three ortwo atoms, products of no technical interest are formed-as, forinstance,according to the directions of the German Patent No. 132,212, whichprescribes even less than two atoms of sulfur.

When boiling the above-mentioned indophenols in an aqueous solution withsuch quantities of sulfur and sodium sulfid as according to ouraforestated observations are essential, a coloring-matter of hightechnical value is obtained which renders it possible to obtain fastindigo-like shades on cotton.

The manufacture of our dyestuif is illustrated by the following example:Thirty kilos of the sodium salt of the indophenol OHO H N =O H =O areslowly added at about 80 centigrade to one hundred and eighty liters ofan aqueous solution containing one hundred and twenty kilos ofcrystallized sodium sulfid and sixty-six kilos of sulfur. The solutionobtained is heated up to boiling in a vessel combined with a refluxcondenser and is kept at the boiling temperature for about twenty-fourhours. The mass is'diluted with water and from the solution obtained thedye stuff is precipitated by the introduction of a current of air. It isthen filtered, pressed, and dried. The product thus obtained is abrown-black powder which is insoluble in water. It dissolves in causticalkalies with a dull bluish, in alkali sulfide with blue, color. In warmconcentrated sulfuric acid the dyestuif dissolves with a violet color.

duces on cotton direct dull greenish-blue tints, which by the action ofoxidizing agents are transformed into indigo-blue shades of remarkablefastness.

The following alterations may be made in the above example withoutmaterially changing the character of the product obtained.

It pro- Instead of the typical indophenol its homologues may beemployed, which result, for instance, from the conjoint oxidation ofparaamidophenol and orthocresol or metacresol or in a similar mannerfrom para-amido-orthocresol or para-amidometa-cresol ororthochlor-para-amido-phenol and phenol, oriho or meta cresol.

Having now described our invention and in what manner the same is to beperformed,

What we claim as new is-- 1. The process for the production of anindigo-blue sulfur dye by heating the indophein a boiling aqueoussolution with sulfur and sulfid ofalkali in such proportions that uponone molecule of crystallized sodium sulfid at least four atoms of sulfurare employed. I

2. The indigo-blue sulfur dye obtained as hereinbefore described, saiddye beinginsoluble in water, dissolving in causticalkalies with a dullgreenish-blue color, in alkali sulfids with blue color and in warmconcentrated sulfuric acid with violet color, producing on'

